By means of an already known process, transverse currents can be created in the metal bath by immersing coolers in it to create temperature gradients which then produce convection currents. The intensity of these convection currents is determined by the magnitude of the temperature gradient. Since the temperature gradient is in principle undesirable and can only be produced by means for continuous cooling, only relatively weak currents can be produced and maintained by this process.
By means of another known process, transverse currents can be produced in the metal bath by linear induction motors positioned near the side walls of, and immediately above, the metal bath. A disadvantage of this process is that it is very expensive to maintain electrical induction motors in working condition at approximately 1,000.degree. C.
In the float method of producing flat glass, it is also conventional to use mechanically operating pumps in order to draw off the impurities that form on the surface of the metal bath. These pumps however are installed in a stationary manner outside of the actual tank and are connected to the bath through special pipes and/or bays. They are not used to create currents in the bath.